Trigger mechanism of machine guns and automatic small arms



Nov. 17, 1925.

L. TUCKER TRIGGER MEcHAmsM oF MACHINE Guus AND AuTouAnc sum1.:l ms

Filed July 27. 1925 fw]- /:w 25W/Wwf I Patented Nov. l?, i925.

TRIGGER MECMISM IACENE .To all whom t may concern:

Be it known that I, LEONARD TUCKER, a `subject of the King et Great Britain, residing at la Salcombe Gardens, Clapham Comk mon, in the county of London, England, have invented certain new and useful lmprovements in or Relating to the Trigger Mechanism of Machine Guns and Automatic Small Arms, ot which the following is a specification.

'This invention relates to t-he trigger mechanism ot machine guns and automatic small arms iu which an adjustable device is provided tor enabling the weapon to be Converted, at will, trom an automatic weapon into a single shot weapon, that is to say into a weapon in which only one shot is tired each time the trigger is operated. In known trigger mechanism ot this kind the sear, which holds the firing member (i. e., the striker) in the cocked position, is displaced into the disengaged position by the movement of the trigger, the parts being so arranged that, when the aforesaid device is adjusted to fire single shots, the connection between the sear and the trigger is broken by the continued motion of the latter immediately the tiring member is released. The sear is then returned to its normal position by a spring in readiness to re-engage with the tiring member as soon as the weapon is cocked by its automatic action. It is found in practice that the motion of the trigger is not always continued after the tiring member has been released, with the result that the sear may be held in the Vdisengaged position and two or more shots therefore fired by one operation ot the trigger. This is objectionable as ammuni tion is wasted and the presence ot an automatic weapon may be prematurely disclosed to the enemy. The chief object ot the present invention is to provide a simple and compact trigger' mechanismwhich can be adjusted to automatic lire, and single fire as hithereto, but which will not allow more than one shot to be tired at each operation of the trigger when the aforesaid device is set to single lire.

YAccording to the invention the sear is made longitudinally movable and is placed under the influence of a spring in such a manner that when the said adjustable device occupies the csingle lire position'- and .S AND ATOMT-f" SMALL ARMS.

Serial No. 46,'90

the sear is rocked by the trigger to release the tiring member, the said spring will displace the sear rearwardly into a position in which the sear becomes disengaged irom the trigger irrespective of whether or not any further movement is given to the trigger by the marksman, the sear then rocking into re-engagement with the tiring member as the weapon is recocked. The liability oi more than one shot being fired by a single operation o'l' the trigger is thus obviated. ln the automatic lire position of the said adjustable device a part thereof prevents the above-mentioned rearward movement ot' the sear trom occurring and another part may, at the same time, limit the rocking movement of the sear to release the firing member.

In order that the said invention may be clearly understood and readily carried into effect, the same will new be described more fully with reference to the accompanying drawings, in which Figure l is a side elevation of a constructional form ot trigger mechanism in accordance with this invention, the adjustable device being' shewn in the single tire position and the sear in engagement with the tiring member.

Figure 2 is a View similar to Figure l except that the parts of the trigger mechanism are shewn in the position they occupy at the moment of release of the tiring member.

Figure 3 is a view similar to Figure 2 shewing the position of the parts when the trigger is pulled completely back.

Figure 4L is a view similar to Figure l except that the adjustable device is shewn in the automatic fire position, the parts ot the trigger mechanism being in the position they occupy at the moment of release of the tiring member.

Figure 5 is a view similar to Figure l eX- cept that the adjustable device is shewn in the sate position, and

Figures 6 and Z are sections taken on the lines 6, 6 and 7, 7 of Figure 1.

A is the aforesaid adjustable device, E is the iiring member e., the striker). C is the sear which has a nose c for engaging with a bent on the striker B and D is the trigger.

rlhe various members Comprising the trig-I ger mechanism are mounted in a frame E which is preferably made integral with, and forms a forward extension of, the end piece of the weapon. This frame has a detachable side plate El (Figures 6 and 7) which permits easyaccess to be had to the trigger mechanism. The aforesaid adjustable device A is constituted byl an angularly adjustable stop member (of a shape hereinafter described) mounted transversely in the frame and adapted to engage with the side plate E1L by means of a bayonet joint connection yas shewn in Figures 6i and 7 so that by moving the stop member into the dismantle position the side plate El can be withdrawn' from the frame E. The said stop member A has a lever or handle AX in the formfof a flat spring disposed outside the frame, the extremity ofthe spring having asmall inward projection a* (Figure 7) adapted to engage with suitable notches in the frame to determine its' correct positions of which therev are three (apart from the dism'antle"7 position) viZ, the single fire position', the automatic tire positiom and thesafe" position;

The sear C has a slot by which it can slide longitudinally on a block Cl forming part of an axis pin c1 pivoted in the frame E' and has-pivoted at o2 in another slot atits rear part a spring-controlled pawl`C2'the lower end of*` which normally rests on the upper surface ofthe trigger D'which is pivotally mounted atd in the frame- The pawl'C2 is controlled fbya spring c2* interposed between it andthe rearwall of itsslot in the Sear, andthe trigger' D is controlled by a spring Z1 interposed between part: ofthe frame E and atafilpiece D1 on thetrigger. C3 is the scar spring which is interposed between a partof they frame E anda part of the sear in front ofthe axis pini C1. This-:spring is disposed at an angle tothe direction of the sliding movement ofthe `searC so that the said spring serves the dual purpose of resiliently holding the n'ose c of the sear in engagement with the bent blon'the strikerl) and of moving thesear'to its rearmost position when the said nose ofthe sear is disengagedfromithe said benton the striker.

The aforesaid stop member'A is shaped as shewnin the drawings andY when it'occupies the singlelire position-'shewn inFigures 1, 2 and 3 it is entirely out ofthe-path of a downward projection C? on the sear C. Thus'when ythe i nose 0f ofthe .sear C isliberated from the bent b onlthe striker B' (as shown inFigure- 2) by pulling the trigger D, the sear spring: CSL operates to displace the l searC.. towardsthei rear as shewn in Figure (the -sear sliding; upon the I aforesaidblock'iC.1 ena-the aXisfpi'n--.c-1) so as-to Inovel the' aforesaidy pawl C? tout of contact with the upper surface of the trigger.; D@ it being; umilerstmxl` thattherv angular-L movennve ments of the trigger D and the Sear C when the trigger was pulled has materially reduced the normal area of contact between the upper surface of the trigger and the pawl C2 as vwill be seen by a comparison between Figures l and 2. rlhe striker B has now moved forward to tire the gun and the sear C is free to rock under the upward pressure of the sear spring C until the Sear regains its normal position ready for its nose c to re-engage with the bent on the striker B on the return movement of the latter, the sear being depresed against the action of its spring Cby the co-operation of an inclined surface 1 on the striker with the nose c of the sear. Then the nose c and the bent t) re-engage the forward pressure of the striker spring moves the sear C longitudinally in a forward direction against the resistance of the spring Ci. lVhen the trigger D is pulled to a position beyond that shewn in Figure 2 into the position shewn in Figure 3 and held in the latter position until the sear C has been moved in a forward direction as above described, the front lower part of the pawl C2 will bear against a shoulder (Z2 on the trigger and the pawl will thus be displaced to the rear about'its pivot c2 and against the resistance of its spring 02X, but will be caused by the said spring to resume its normal position shewn in Figure l'when the pull on the trigger has been released and the trigger returnedto its normal positionA by its spring (1. It will be seen that the sear is disengaged from the trigger imn'iediately the striker has escaped, without any overdraw of the trigger, but in the event of the sear sticking or binding on the block Cl of the axis pin c1 so that the sear is unable to move to the rear under the pressure of its spring C3, a continued movement of the trigger after the striker has been released will cause the upper surface of the trigger to slip from under the pawl C2. The movementof the trigger will then be arrested by atoe D2 thereon coming into contact with the stop member A andthe scar is free to rock under the influence of its spring to reengage with the bent on the striker. )When the pull'on the trigger is released the aforesaid shoulder'rl2 thereon presses against the frontlower portion of the pawl C2 which is thusswung about its axis-pin c2 to allowlthe trigger tol pass. As soon as the trigger has regainedl its normal position shewn in Figurel lV the pawl spring c2* returns the Jawl= C2 to itsnormal positionk shewn iu ligure '1.

When' the stop member A occupies tha` automatic fire position, shewn iii-Figure et? al cornerorprojection a; thereon bears againstor is Yarranged verv close to the rear surface of the aforesaid downward projecti'enlC-f onthespear C- so asfto hold'` the latterin.; ieg: fQrwar-ds ,positionwithout; however.

impeding its rocking movement about the axis pin c1. As the sear C cannot move rearwards under the influence of its spring C3, the pawl C? will remain in contact with the upper surface of the trigger l) and consequently the weapon lires .uton'iatically so long as the pull on the trigger is maintained. The stop member A has a second corner or projection al which, in the automatic lire position, limits the downward movement ot the sear C as shewn in Figure -t and thereby prevents the pawl C2 .from becoming` disengaged from the upper surface ot the trigger D by excessive movement of the latter.

lVhen the stop member A occupies the sate position shewn in Figure 5 the corner or projection ,al on the said member bears against the toe D2 of the trigger D. The trigger is thereby locked in its normal position and cannot be moved in the direction to operate the sear, but at the same time the sear C remains free to move so that in lthe event of the weapon being manually cocked with the stop member i occupying the sale position, the sear can be rocked on its anis pin c1 by the co-opera-tion of the inclined surface b1 on the striker B with the nose c or the sear so as to enable this nose to engage in front of the bent Z9 on the striker, the engagement being effected by the sear spring C3.

lVhat I claim and desire to secure by Letters Patent of the United States is l, In trigger mechanism for machine guns and automatic small arms having an adjustable device .tor enabling the weapon to be converted, at will, from an automatic weapon into a single lire weapon, the combination with the trigger, the pivoted sear and the firing member with which said sear engages, of means for mounting said scar so that it can move bodily as well as rock about its pivot, and a spring which, when said adjustable device occupies the single liref7 position, moves said sear in a rearward direction, when disengaged from the liring member, so as to disengage it from the trigger.

In trigger mechanism for machine guns and automatic small arms having an adjustable device for enal'iling the weapon to be converted, at will, from an automatic weapon into a single lire weapon, the combination with the trigger, the pivoted scar and `the firing member with which said sear engages, of means 'tor mounting said sear so that it can more longitudinally, and a spring which, when said adjustable device occupies the single tire position, moves said sear rearwardly, when disengaged irom the liring member, so as to disengage it from the trigger.

3. lin tri 1Y0-er -gg mechanism for machine guns and automatic small arms having an adjust-able device for enabling the v'weapon to engaged trom the liring member, to break.

the operative relationship between the trigger and the pawl.

il. ln a trigger mechanism for machine guns and automatic small arms having an adjustable device for enabling the weapon to be converted, at will, from an automatic weapon into a single tire weapon, the combination with the trigger, the pivoted sear 'and the tiring member' with which said sear engages, of means for mounting said sear so that it can move longitudinally as well as rock about its pivot, a spring-controlled pawl carried by said sear and normally ar ranged in operative relationship with said trigger and a spring which, when said adjustable device occupies the single tire position, moves said sear rearwardly, when disengaged from the iiring member, to carry said pawl out of operative relationship with respect to the trigger.

5. ln trigger mechanism for machine guns and automatic small arms having an adjustable device 'for enabling the weapon to be converted, at will, lrom an automatic weapon into a single fire weapon, the combination with the trigger, the pivoted scar and the firing member with which said s-ar engages, of means for mounting said sear so that itcan move longitudinally, and a spring which, when said adjustable device occupies the single tire position, moves said sear rearwardly, when disengaged from the firing member, so as to disengage it from the trigger, and a projection on said adjustable device serving, when said dev'ce occupies the automatic lire7 position, to prevent said sear from moving real-wards.

6. ln trigger mechanism for machine guns and automatic small arms having an adjustable device `lier enabling the weapon to be converted, at will, from an automatic weapon into a single tire weapon, the combination with the trigger, the pivoted sear and the firing member with which said sear engages, ot means for mounting said sear so that it can move longitudinally, and a spring which, when said adjustable device occupies the single tire position, moves said sear rearwardly, when disengaged from the iring member, so as to disengage it from the trigger, and projections on said adjustable device serving, when said device occupies the automatic tire position, to prevent said Sear from moving rearwards and to limit tlie rocking movement of said Sear to release the firing member.

7. In trigger mechanism for machine guns and automatic small arms having an adjustable device for enabling tlie Weapon to be converted, at will, from an automatic Weapon into a single tire Weapon, the combination with the trigger, the Sear and the 10 firing member with which said Sear engages,

of means for mounting said Sear so that it can move longitudinally in addition to performing its movement into and out of engagement with said iring member, and a spring which7 when said adjustable device occupies the single tire position, moves said Sear ir. a rearward direction, when disengaged i'om the tiring member, so as to dieengage it from the trigger.

LEONARD TUCKER. 

